Authorities in the northeastern Mexican state of Nuevo Leon said they are investigating a possible breakout at a prison where 44 inmates died in a fight involving members of the rival Gulf and Los Zetas drug cartels.

The spokesman for the state’s Security Council, Jorge Domene, said 17 guards in the Apodaca correctional facility’s cell block D have been detained over the alleged prison break, as have the facility’s director, deputy director and security chief.

“In comparing the inmate list, we haven’t ruled out a prisoner escape,” Domene said in a press conference, adding that the riot may have been staged to distract attention away from the prison break.

Domene read out the names of 10 of the victims and said work was continuing to identify the others. He said they would be announced 10 at a time and asked for understanding from the inmates’ family members.

The official said the prison was 80 percent overcrowded and that the number of inmates in cell block D was double its capacity.

Most of those killed in the fight in Sunday’s wee hours were members of the Los Zetas cartel.

The Zetas, a band of special forces deserters turned outlaws, spent years as the armed wing of the Gulf drug cartel before going into business for themselves.

A territorial battle between those two drug cartels and clashes pitting criminals against the security forces claimed some 2,000 lives in Nuevo Leon last year.

The fight started around 2:00 a.m. Sunday in the prison in Apodaca, a suburb of Monterrey, the capital of Nuevo Leon, Domene said earlier.

Gunfire was heard during the fight, but officials have not determined whether it came from guards or inmates.

Federal and state security forces regained control of the prison Sunday morning and the Nuevo Leon state government set up an area to assist inmates’ relatives, who gathered around the prison seeking information about loved ones

Sunday’s fight produced the largest death toll from an incident of this type in the past few years in Mexico.

A fight last month at a prison in the northeastern state of Tamaulipas left 31 inmates dead.

A fire apparently caused by a short-circuit at the prison in Apodaca left 14 inmates dead and 35 others injured on May 20.